FIG. 1 is a simplified diagram showing the layout of a conventional two-dimensional capacitive touchpad 10 which includes capacitance sensor traces TX1-TXN in X-direction and TY1-TYM in Y-direction. For such capacitive touchpad 10, conventional methods for touch point detection is to detect the self capacitance from each of the capacitance sensor traces TX1-TXN and TY1-TYM, and then the position at which the detected capacitance has the maximum variation is determined as the touch point. However, such methods can only detect a single touch point each time, but cannot be effective for multi-touch applications. For example, as shown in FIG. 2, when two fingers touch the capacitive touchpad 10 simultaneously, in addition to the real touch points 20 and 22, there will be two ghost points 24 and 26 being detected as touch points simultaneously. In further detail, when the fingers touch at the positions 20 and 22, it causes the self capacitances of the capacitance sensor traces TX1, TX2, TY1 and TY2 having peak variations simultaneously, from which four touch points (TX1, TY1), (TX2, TY1), (TX1, TY2) and (TX2, TY2) will be identified. This case makes it impossible for a capacitive touchpad 10 to properly identify the real touch points 20 and 22 from the multiple detected touch points 20-26.
Therefore, it is desired a detector and method for a capacitive touchpad to distinguish a real touch point from a ghost point.